1. Field of the Invention
This invention relates to photographic apparatus and more particularly to a film cassette loading door latch and interlock switch for use with a fully automatic camera.
2. Description of the Prior Art
Convenience in the use, handling, and storage of amateur photographic systems is related to their size and the amount of operator effort involved in taking a picture and obtaining a finished print. A convenient photographic system, therefore, may be characterized as one comprising a compact camera and film combination requiring only nominal operator participation in the production of a finished print.
A great many photographic systems have been developed which approach the goal of convenience in a variety of ways. One such system, a self-developing type, is disclosed in the patent literature.
In U.S. Pat. No. 3,714,879 entitled "Reflex Camera" issued to Edwin H. Land, et al., on Feb. 6, 1973, is shown and described a fully automatic, single-lens reflex camera capable of being folded into a thin, compact shape suitable for convenient carrying in the pocket of a garment. This camera is intended to be used with a disposable film cassette including an integrated power supply. Such a cassette is described in considerable detail in, for example, U.S. Pat. Nos. 3,543,662 issued Dec. 1, 1970; 3,651,746, issued Mar. 28, 1972; and 3,705,542 issued Dec. 12, 1972. These latter patents describe photographic film assemblages each of which basically comprise a cassette, an opaque light shield or dark slide, and a plurality of film units, preferably of the self-developing type, arranged in stacked relation and adapted to be exposed and then automatically withdrawn from the cassette and processed in sequential fashion. The power supply, forming an integral part of the cassette, is a battery which supplies electrical energy for the operation of components of the camera in which the film units are exposed and processed. The camera includes various subsystems whose functions closely correspond to those steps a user would normally perform in a conventional photographic process. Such subsystems include, for example, the exposure control system, film-transport system, dark slide removal system, a motor-powered mechanism for processing an exposed film unit, and electronic logic circuits that provide a sequence control function.
The cassette is directly inserted into a receiving chamber formed by the base of the camera. The bottom of the chamber includes a pair of contacts adapted to engage the terminals of the battery of the cassette when it is disposed within the chamber and an upper portion which, in cooperation with the cassette structure, defines the exposure plane of the camera. After the cassette is inserted into the chamber, a pivotally mounted loading door is swung into a position where it blocks the receiving chamber entrance.
As a consequence of the nature of the cassette and the automated camera concept aimed at user convenience, it is desirable, as an adjunct to swinging the loading door into its blocking position, to have the dark slide automatically ejected so as to uncover a film unit and make it ready for exposure while at the same time have the loading door latched in a positive manner. An interlock function responsive to the latched door condition provided by a switch intermediate and in power supplying relation between the battery and other camera subsystems is also a highly desirable feature as it assures that all conditions for sequential operation are satisfied. Further, the latch must have the capability of being manually unlatchable to renew the cassette.
U.S. Pat. No. 3,760,701 entitled "Photographic Apparatus With Delayed Interlock Switch" issued to Richard Paglia on Sept. 25, 1973 discloses apparatus satisfying these requirements. The invention disclosed there may be characterized as a logical AND device in that the switch does not electrically couple the battery to the system circuitry until two mechanical conditions are satisfied. Specifically, these conditions are that: (1) the door be in the closed position and (2) the latch be in its locked position. In accordance with the present invention it will be seen that all these requirements are still satisfied by the elimination of the logical AND nature of the switch described in the cited prior art and the replacement of it with a highly reliable simplified switch/latch mechanism that is binary in nature and uses fewer moving parts.